Maurice Girodias published most of Trocchi's novels through Olympia Press,[2] often written under pen names, such as Frances Lengel and Carmencita de las Lunas.

Girodias also published My Life and Loves: Fifth Volume, which purported to be the final volume of the autobiography of Irish writer Frank Harris. However, though based on autobiographical material by Harris, the book was heavily edited and rewritten by Trocchi.[3]

Maurice Girodias commissioned him to write erotica. Under the name Frances Lengel, Trocchi churned out numerous pornographic books including the now classic Helen and Desire (1954) and a dirty version of his own book Young Adam (1954). Trocchi and his friends also published Samuel Beckett’s War and Memory and Jean Genet’s Thief’s journal in English for the first time. [4]

Trocchi acquired his lifelong heroin addiction in Paris. He left Paris for the United States and spent time in Taos, New Mexico, before settling in New York City, where he worked on a stone scow on the Hudson River. This time is chronicled in the novel Cain's Book, which at the time became something of a sensation, being an honest study of heroin addiction with descriptions of sex and drug use that got it banned in Britain, where the book was the subject of an obscenity trial; in America, however, it received favourable reviews.

Trocchi was then deep in the thralls of heroin addiction; he even failed to attend his own launch party for Cain's Book. His wife Lyn prostituted herself on the streets of the Lower East Side. He injected himself on camera during a live television debate on drug abuse, despite being on bail at the time. He had been charged with supplying heroin to a minor, an offence then punishable by death. A jail term seemed certain, but with the help of friends (including Norman Mailer), Trocchi was smuggled over the Canadian border where he was given refuge in Montreal by poet Irving Layton and met up with Leonard Cohen. His wife Lyn was arrested and son Marc detained, but later joined Trocchi in London.

In the late 1950s he lived in Venice, California, then the centre of the Southern California Beat scene. In October 1955, he became involved with the Lettrist International and then the Situationist International. His text "Invisible Insurrection of a Million Minds" was published in the Scottish journal New Saltire in 1962 and subsequently as "Technique du Coup du Monde" in Internationale Situationniste, number 8. It proposed an international "spontaneous university" as a cultural force and marked the beginning of his movement towards his sigma project, which played a formative part in the UK Underground. He resigned from the SI in 1964.

Trocchi appeared at the 1962 Edinburgh Writers Festival where he claimed "sodomy" as a basis for his writing. During the festival, Hugh MacDiarmid denounced him as "cosmopolitan scum." However, while this incident is well known, it is little remarked upon that the two men subsequently engaged in correspondence, and actually became friends. Trocchi then moved to London, where he remained for the rest of his life.

He began a new novel, The Long Book, which he did not finish. Much of his sporadic work of the 1960s was collected as The Sigma Portfolio. He continued writing but published little. He opened a small book store near his Kensington home. He was known in Notting Hill as "Scots Alec". He died of pneumonia in London on 15 April 1984.

In the 1960s Trocchi lived in Observatory Gardens, Kensington, London on the two top floors of a 19th-century terrace block comprising six stories. He had two sons: Marc Alexander Trocchi and a second son, Nicholas. The elder son, Marc died of cancer at age 19 in 1976, shortly after Alexander's American wife Lyn died of complications from hepatitis. The final tragedy was the suicide of the younger son, Nicholas who, some years after his father's death, returned to the family's home in London and leapt from the top floor of the five-storey building to his death. When the terrace block was extensively refurbished into luxury apartments in the 1980s the number on Alexander Trocchi's house was removed, possibly to avoid the house becoming some form of shrine.

Interest in Trocchi and his role in the avant-garde movements of the mid-20th century began to rise soon after his death. Edinburgh Review published a "Trocchi Number" in 1985 and their parent house published the biography, The Making of the Monster by Andrew Murray Scott, who had known Trocchi for four years in London and who went on to compile the anthology, Invisible Insurrection, in 1991, also for Polygon. These works were influential in bringing Trocchi back to public attention. Scott assisted the Estate in attempting to regain control of Trocchi's material and to license new editions in the UK and US and Far East, also collating and annotating all remaining manuscripts and documents in the Estate's possession.

During the 1990s, various American and Scottish publishers (most notably Rebel Inc.) reissued his originally pseudonymous Olympia Press novels and a retrospective of his articles for Merlin and others, A Life in Pieces (1997), was issued in response to revived interest in his life and work by a younger generation. His early novel Young Adam was adapted into a film starring Ewan McGregor and Tilda Swinton in 2003 after several years of wrangling over finance.

Tainted Love (2005) by Stewart Home contains a lengthy 'factional' meditation on Trocchi's post-literary career period in Notting Hill. In 2009 Oneworld Publications reissued Man at Leisure (1972), complete with the original introduction by William Burroughs, and in 2011 Oneworld Publications also re-released Cain's Book, with a foreword by Tom McCarthy.